The gene clusters encoding various P-fimbriae (F7(1), F7(2), F9 and F11) were compared. Deletion plasmids that lack the gene encoding the fimbrillin were derived from these gene clusters. Introduction of these deletion plasmids into an E. coli K12 strain resulted in non-fimbriated cells that still showed mannose-resistant hemagglutination (MRHA). However when introduced into wild type E. coli strains no MRHA was observed. Derivatives of the wild type E. coli strains with reduced amounts of O-antigen on the other hand showed MRHA when harbouring these plasmids. These results indicate that adhesion and presence of fimbriae are not necessarily linked. P-fimbriae could function as a carrier for the adhesin and thus endow adhesive capacity to cells with a complete O-antigen.